Hi,some calculations. I looked Pictures and find The boiler manufacturer. I did go to website to Look and found data sheets.
There is a different sizes of them,but Same as on Pictures looked smaller ones.
Sino says that boiler Works with diesel oil
Datasheet says consumes about oil about 100kg/h (varies 60-1000 depends on boiler size)
1L petrol costs 1,2$ on China(googled)
(1L not accurate 1kg)
100kg/h*1,2*24*30=86000$/month
Power is 1 Mw
Have to later calculate how much need Power to keep pools about 8 degrees over Air temperature..1 kg oil is 10300 kcal.
This was very fast calculations,but maybe would costs at full Power 100 000$/month. Just little direction and scale..
Maybe looks that this foil can is enough and usable.
Maybe it seems that heating costs are not significant. I feel quite optimistic now